The turbo blower is a machine which revolves an impeller at high speed by means of a motor to draw external air and blow it. The turbo compressor is the same machine as the turbo blower, however, the term of the turbo compressor is used when the discharging pressure is high. If the pressure is less than 1 bar we usually call it turbo blower and if the pressure is over 1 bar we usually call it turbo compressor.
The turbo blower is generally used for pneumatic conveying or aeration at a sewage disposal plant so on and the turbo compressor is used for pneumatic conveying or supplying pressurized air to pneumatic equipment and so on.
In the present invention, the term of the turbo blower includes the turbo compressor.
The pressure of the emission air is low at early stage of operation of the turbo blower since the motor does not reach the steady state and it is difficult to use the air. For example, the emission air pressure at the early stage is too low to use for the aeration. Accordingly, the air is blown off to the atmosphere until the motor reaches the steady state. After the motor reaches the steady state, the air is emitted to the originally-intended place.
For this purpose, conventionally, a butterfly valve has been used, which requires a compressor and an actuator. The compressor generates high pressure air to operate the actuator for the butterfly valve. The actuator operates the butterfly valve to blow off the air at the early stage of the turbo blower and emit the air to the originally-intended place after the turbo blower reaches the steady state.
However, in this case, electricity rates are wasted for the operation of the compressor. Further, the compressor may cause a problem, which leads to the problem of the turbo blower. Furthermore, tube connecting the compressor and the butterfly valve occupy space, the length of the tube may be the problem and installation of a separated power source is required for the operation of the compressor, all which causes complication. Therefore, it is desirable if the blow-off the air is performed without the compressor. The present invention satisfies this demand.